CPU temperature high when rendering with the GPU
Turn off the CPU in the GPU render by going into Preferences > System, and under the CUDA Settings, uncheck the CPU.

I noticed this, too. I'll say that, under the same load, with similar effects and raytracing options, Blender renders, CPU, GPU, or shared, run hotter than in other software, for me.

Blender renders hit 90+ degrees after five or so minutes. Cinema 4D doesn't really go beyond 84 degrees.